Whilst in the quest to upgrade my mirrors to power folding ones, finally figured out how to take apart the Post Ford mirror!
Start by removing the mirror unit from the car; remove inside cover plate (flathead does this) and undo 3 bolts/screws. Disconnect wiring behind door card, feed through and mirror should come away. Next, unclip the outer cover and finally remove the glass itself (it clips in tightly but should pull out ok)
Now this took a good deal of playing and wiggling, but basically to take it apart I used:
- Philips/crosshead screwdriver
- Long nose plyers
and that's pretty much it!
Getting the mirror off of the mount has nothing to do with any of the screws (annoyingly). Turns out it's a locking washer thing on the bottom of the shaft held on tight by a big spring.
To get at it remove the large cap at the bottom of the shaft:

This reveals the washer in question:

You should see a little indent at the bottom of the washer. There is also one on the opposite side, hidden by the loom. Now to undo this I, eventually, placed the mirror on the floor between my knees with the mount facing away from me. I then used long nose plyers, located in the indents, to press down firmly and rotate the washer, counter clockwise if I remember correctly. When it does undo, watch for 3 small ball bearings coming out from between the mirror and base!!
You should end up like this:

I used long nose plyers as they worked, I guess you can use whatever allows you to press down and rotate the washer using those indents.
The shaft should come away so:

To remove the mirror mount itself, undo these 3 screws and extract:

To take out the inner part (no idea what you call it), remove these four screws and wiggle out:


This should leave this:

Obviously the wiring loom is still in there and, short of cutting off one of the plugs on the end, it won't fit thought the holes the loom routes through.
I'm sure this is the hole for the power fold motor:

I also noticed that what appears to be the bit that stops the mirror wobbling too much was pretty worn away:

And on this one (from a scrapper) part of the mount was broken off (you can see the curved piece that's off of where it should be)
Reassembly is pretty much the reverse tbh, though locating those ball bearings is a bit of a bugger, well, making them stay in there is!
All I have to do now is get hold of a power folding mirror from another Mazda (626, BJ, Xedos or like) and see if the two will marry up!